. Plant studies; an elementary botany. Botany. 200 PLANT STUDIES ravages of animals (see §105). Examine Figs. 176, 177, 178, 179, 180, 181. 142. Anatomical adaptations.—It is in connection with the xerophytes that some of the most striking anatomical adaptations have been developed. In such conditions the epider- mis is apt to be cov- ered by layers of cuticle, which are de- veloped by the walls of the epidermal cells, and being constantly formed beneath, the cuticle may become very thick. This forms a very efficient protective covering, and has a tendency to diminish the loss of water (see §3
. Plant studies; an elementary botany. Botany. 200 PLANT STUDIES ravages of animals (see §105). Examine Figs. 176, 177, 178, 179, 180, 181. 142. Anatomical adaptations.—It is in connection with the xerophytes that some of the most striking anatomical adaptations have been developed. In such conditions the epider- mis is apt to be cov- ered by layers of cuticle, which are de- veloped by the walls of the epidermal cells, and being constantly formed beneath, the cuticle may become very thick. This forms a very efficient protective covering, and has a tendency to diminish the loss of water (see §35). It is also to be observed that among xerophytes there is a strong de- velopment of palisade tissue. The working cells of the leaves next to the exposed surface are elongated, and are directed endwise to the surface. In this way only the ends of the elongated cells are exposed, and as such cells stand very closely to- gether, there is no drying air between them. In some cases there may be more than one of these palisade rows (see §32). It has been observed that the chloroplasts in these palisade cells are able to assume various positions in. Fig. 177. Two plants of common goree or fnrze (Ulez), showing the effect of environment : b is a plant grown in moist conditions; a is a plant grown in dry conditions, the leaves and branches having been almost entirely developed as thorns.—After Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Coulter, John Merle, 1851-1928. New York, D. Appleton and Company
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